Copolymerization of alpha-olefins and dienes by ziegler-natta type catalysts formed in the presence of unsaturated polymers



1969 c E. P. v. VAN DEN BERG ETTAL 3.472,823

COPOLYMERIZATIOiJ 0F ALPHA-OLEFINS AND DIENES BY ZIEGLER-NATTA TYPECATALYSTS FORMED IN THE PRESENCE OF UNSATURATED POLYMERS Filed June 1,1965 United States Patent 3,472,823 COPOLYMERIZATION 0F ALPHA-OLEFINSAND DIENES BY ZIEGLER-NATTA TYPE CATALYSTS FORMED IN THE PRESENCE OFUNSATURATED POLYMERS Cornelis E. P. V. van den Berg, Geleen, and RoelofFidder, Heerlen, Netherlands, assignors to Stamicarbon N.V., Heerlen,Netherlands Filed June 1, 1965, Ser. No. 460.043 Claims priority,application Netherlands, June 2, 1964, 6406167 Int. Cl. C08f 1/08, 1/32US. Cl. 260-8058 ABSTRACT or TIIE DISCLOSURE A process of preparingunsaturated copolymers from l-alkenes and hydrocarbons having more thanone double bond by the utilization of coordination catalysts isdescribed wherein the catalyst component is mixed with an unsaturatedcopolymer thereby reducing the energy required to stir the reactionmixture, obviating the formation of a catalyst activity reducingprecipitate, increasing the yield of polymer formed, reducing the amountof polymer sticking to the reaction vessel, and increasing the speed ofpolymerization. If the copolymer formed is unsaturated, it is preferredto recirculate a portion of this unsaturated copolymer as the initialcopolymer to be mixed with the catalyst. The amount of unsaturatedcopolymer used is that amount sufficient so that no precipitate isformed, and the preferred amount is 20-200 22 Claims mg. per mmol of theorgano-metallic catalyst component.

The present invention relates to a process for preparing unsaturatedcopolymers, in which a mixture of at least one alkene-l with the generalformula RCH CH where R represents a hydrogen atom, an alkyl, aryl,aralkyl, or alkaryl group, or a cyclo-alkene, and at least onehydrocarbon with more than one double bond is polymerized in the liquidphase with the aid of a co-ordination catalyst containing anorganometallic compound of a metal of the Groups I to III or of GroupIV-B and a compound of a heavy metal of the Groups IVA-VIIA or of GroupVIII of the Periodic System of the Elements according to Mendeleef.

It is common knowledge that, like natural rubber, these unsaturatedcopolymers can be vulcanized with sulphur or with analogous vulcanizingagents. However, the quality of the products thus obtained stronglydepends on the conditions under which the polymers have been preparedand in particular on the ratio between the organometallic compound andthe heavy-metal compound during the polymerization. Only if this ratiois greater than a given minimum value, usually greater than unity, cancopolymers be obtained that are readily vulcanizable so that productswith good mechanical properties can be prepared from them.

In a continuous process for the polymerization the catalyst componentsare usually fed separately to the polymerization reactor and then mixedherein. However, the liquid contained in the reactor is very difiicultto stir due to the fact that for economicalreasons the polymerization isso carried out that a concentrated suspension or solution of thecopolymer is obtained. This makes it very difficult, if not impossible,to mix the catalyst components so rapidly that the ratio between theorganometallic compound and the heavy-metal compound is prevented frombecoming locally appreciably smaller than is required for preparing agood product. Another drawback of mixing the catalyst components in thereactor is 3,472,823 Patented Oct. 14, 1969 that the reactor becomesvery fouled, so that it has to be cleaned repeatedly.

It has also been previously proposed to mix the catalyst componentsoutside the reactor, whether or not in the presence of the monomers tobe polymerized. Naturally, this offers the advantage that the mixing canbe accomplished in a liquid that can be easily stirred. However,applicant has found that in such a process a precipitate is alwaysformed which reduces the activity of the catalyst and makes it morediificult to remove the catalyst residues from the polymer. Moreover,heavy fouling of the reactor is also observed in this case.

It is an object of the present invention to provide a process by meansof which the catalyst components can be mixed outside the reactorwithout a precipitate being formed. It is a further object of theinvention to provide a process in which the catalyst residues can beeasily removed from the polymer.

A still further object of the invention is to provide a process by whichfouling of the reactor is counteracted. Another object of the inventionis to provide a process which gives higher yields than the knownprocesses. Still another object of the invention is to provide a processwherein the residence time of the catalyst and the monomers in thepolymerization zone i much smaller than in the known processes. Otherobjects of the invention will appear hereinafter.

It has now been found that the above objects can be achieved by mixingthe catalyst components in the presence of a soluble unsaturatedpolymer.

The process according to the invention for preparing unsaturatedcopolymers, wherein a mixture of at least one :alkene-l with the formulaRCH=CH where R represents a hydrogen atom, an alkyl, aryl, aralkyl, oralkaryl group, or a cyclo-alkene, and at least one hydrocarbon with morethan one double bond is polymerized in the liquid phase with the aid ofa co-ordination catalyst containing an organometallic compound of ametal of the Groups I to III or of Group IVB and a compound of a heavymetal of the Groups IVAVIIA or of Group VIII of the Periodic System ofthe Elements according to Mendeleef, is characterized in that the saidcatalyst components are mixed with each other in a liquid medium in thepresence of such an amount of a soluble unsaturated polymer that noprecipitate is formed, and are subsequently passed into thepolymerization Zone.

The amount of the unsaturated polymer necessary to prevent the formationof a precipitate can be determined by simple experiments. Usually anamount of 20-200 mg. per mmol of the organometallic compound suflices.However, larger amounts may be used without any objection. Althoughother soluble unsaturated polymers such as polybutadiene andpolyisoprene, have the same effect, use is preferably made, of thecopolymer formed in the polymerization, when a soluble copolymer isformed. This is simpler from a technical point of view, as a solution ofthe copolymer is already available in the form of the reaction mixture,so that part of this can be used for mixing the catalyst components. Inthe mixing use may be made of the solvents that are normally employed inthe preparation of the copolymers.

By preference, all or part of the monomers, in the ratio in which theyare to be passed into the reaction zone, are also mixed with thecatalyst outside the polymerization zone. This ensures that at themoment when the catalyst enters the polymerization zone, it is incontact with a mixture of monomers of the composition that is desiredfor obtaining a good product. This is of particular importance, becausethe activity of the catalyst is highest immediately after the catalysthas formed and then rapidly decreases.

The molar ratio in which the organometallic compound and the heavy-metalcompound are mixed may vary from 1:1 to 100:1, but preferably rangesbetween 1:1 and 20:1. The concentration of the organometallic compoundin the mixture usually ranges between 1 and 100 mmoles per litre ofsolvent, but higher concentrations may also be used. The temperature atwhich the catalyst components are mixed with each other and, if sodesired, with the monomers usually ranges between 100 and +80 C. Themixing is preferably effected at a temperature below C. to prevent thecatalyst from losing a large part of its activity, or, if the monomersare mixed with the catalyst outside the reactor, to prevent thepolymerization from beginning outside the reactor; and the mixture ispassed into the polymerization zone as soon as possible after itspreparation, preferably within 15 minutes and, if possible, within 1minute.

The process according to the invention can in general be used in thepreparation of polymers consisting of at least one alkene-l, or acyclo-alkene, and at least one bydrocarbon with more than one doublebond. Suitable alkenes-l are, e.g., ethylene, propylene, butene-l,pentene-l, 4-methyl pentene-l, hexene-l, dodecene-l, and styrene, andsuitable cyclo-alkenes are, e.g., cyclobutene and cyclopentene. Examplesof hydrocarbons with more than one double bond are butadiene, isoprene,pentadiene-l,4, hexadiene-l,4, 2-phenyl hexadiene-l,5, octadiene-l,5,monovinyl cyclohexene, trivinyl cyclohexane, cyclopentadiene,dicyclopentadiene, cyclooctadiene, cyclododecatriene, S-alkenyl2-norbornenes, and 2-alkyl 2,5- norbornadienes. The process isparticularly suitable for preparing copolymers containing ethene andpropene and, as a third constituent, a hydrocarbon with nonconjugateddouble bonds, such as dicyclopentadiene, cyclooctadiene, orhexadiene-1,4.

The polymerization may be carried out in the usual way. Theorganometallic component of the catalyst is preferably an aluminumcompound, such as triethyl aluminum, di-isobutyl aluminum hydride,di-ethyl aluminum chloride, mono-ethyl aluminum dichloride, or ethylethoxy aluminum chloride, and the heavy-metal compound is preferably avanadium compound, such as vanadium tetrachloride, vanadiumoxytrichloride, vanadyl bisacetalacetonate, and vanadyl tri-alkoxides.Especially the combination of mono-ethyl aluminum dichloride or of amixture of monoethylaluminumdichloride and diethylaluminummonochlorideand vanadium oxytrichloride are very suitable catalysts. The catalystcomponents may also be used in combination with Lewis bases, such asethers, amines, phosphines, arsines, stibines, and the like.

The polymerization may be carried out in a solvent, such as hexane,heptane, benzene, gasoline, kerosene, dichloromethane, ethyl chloride,or 1,2-dichloroethane. It is also possible for one or several of themonomers to be polymerized to serve as solvent, the temperature and thepressure being then so chosen that the monomers are kept in the liquidstate. The temperature usually ranges between 100 and +l00 C.,preferably between and +60 C. The pressure may be 1 atmosphere orhigher, but is usually lower than 100 atm.

The process of the present invention is advantageously carried out in acontinuous manner, as for instance by dissolving the catalyst componentsand the monomers to be copolymerized in a suitable inert medium, passingthis solution through a polymerization zone at a suitable rate, addingfresh monomers and catalyst components to a part of the solution leavingthe polymerization zone and recirculating this part to thepolymerization zone.

Mixing of the catalyst components and the monomers with the solutioncontaining the polymer is carried out conveniently in the feed pipe forthe polymerization zone, preferably by means of an inline-blender. Inthis way said mixing can be completed very fast, using a relativelysmall amount of energy, as compared to mixing in a polymerizationreactor or in a separate mixing vessel.

Since the catalyst components are mixed with each other, and preferablyalso with the monomers, outside the polymerization zone, the catalyst isalready very active on entering therein. The applicant has found that asa result thereof the residence time in the polymerization zone can bemuch shorter than in other processes, wherein said zone is also used formixing the catalyst components and the monomers. According to thepresent invention, polymerization times of less than one minute andoften of only 10-20 seconds can be used advantageously.

As a further consequence thereof, the size of the polymerization vesselcan be greatly reduced, since the vessel need not be stirred, whichgreatly improves the economy of the process. It is even possible to useno special polymerization vessel at all, and according to a preferredembodiment of the process according to the invention, the polymerizationis carried out by simply passing the mixture of the catalyst componentsand the monomers at the desired temperature through a pipe of suitablelength.

It is also an advantage of the process according to the presentinvention that, in comparison with other processes, the organometalliccompound and the heavy-metal compound can be used in relatively lowmolar ratios without impairing the catalyst activity. Preferably, saidcompounds are used in a molar ratio between 6:1 and 3:1.

The following examples will serve to elucidate the invention withoutrestricting it.

Example 1 A number of experiments were carried out using a glassthree-neck 500 ml. flask provided with a stirrer and a gasinlet tube andcontaining 200 ml. of dry hexane, in which, two or more of the followingcomponents were dissolved at room temperature: C H AlCl VOCldicyclopentadiene (DCPD), a saturated copolymer consisting of 52% byweight of ethylene and 48% by weight of propylene, an unsaturatedcopolymer consisting of 51% by weight of ethylene, 45% by weight ofpropylene, and 4% by weight of DCPD, and a gas mixture consisting of 50%by volume of ethylene and 50% by volume of propylene. These substanceswere added in such amounts that the final concentrations of C H AlClVOCl and DCPD in the liquid were 10, 2, and 15 mmoles/litre,respectively, and those of the copolymers 2. g./litre, the hexane beingvirtually saturated with the gas mixture.

The results are compiled in the table below. In this table a plus signindicated which substances were added in each experiment, the formationor non-formation of a precipitate being shown by a plus sign or a minussign respectively. The substances were added in the order in which theyare mentioned in the table from left to right.

Ethylene] propylene Saturated Unsaturated Experiment CQHEAICIZ gasmixture copolymer copolymer V001 DCPD Preeipitate i i From experimentsA, B, and D it appears that a precip itate always forms if the twocatalyst components C H AlCl and V001 are brought together whether ornot in the presence of the hydrocarbon with more than one double bond(DCPD). However, if an unsaturated copolymer is also present, noprecipitate is formed (experiments F, G and H). Curiously enough theformation of a precipitate cannot be prevented by the addition of asaturated copolymer (experiment E).

Example 2 The experiments of Example 1 were repeated with the differencethat, instead of cyclopentadiene, cyclooctadiene was used as a monomer.The results were the same. Here, too, the formation of a precipitatecould be prevented only by the presence of an unsaturated polymer.

Example 3 Two series of experiments were carried out in the same way asin Example 1 with the difference that, instead of C H AlCl (C H AlCl wasused in one series and tri-isobutyl aluminum in the other. The resultswere the same.

Example 4 In the same way as in Example 1 two series of experiments werecarried out in which, however, instead of VOCl VCl was used in oneseries and VO(OC H in the other. The results were identical.

Example 5 In a continuous polymerization of a mixture of ethylene,propylene, and dicyclopentadiene, the catalyst components C H A1Cl andVOCl both dissolved in hexane, were mixed in the supply line to thereactor at a temperature of 20 C. in such a concentration that thecatalyst mixture entering the reactor contained 100 mmoles f C H AlCland 10 mmoles of VOCl per litre of hexane. Within 1 minute after beingmixed, the mixture was passed into the reactor in which it was dilutedwith an amount of hexane that was nine times as large and containedmmoles of dicyclopentadiene per litre. Also a gas mixture containing 30%by volume of ethylene and 70% by volume of propylene was passed into thereactor. The polymerization was carried out at a pressure of 1 atm.gauge and a temperature of 30 C. After a mean residence time of about 30minutes the polymer was discharged continuously. This solution contained26 g. of the unsaturated ethylene-propylene-dicyclopentadiene copolymerper litre.

The same experiment was repeated except that the catalyst componentswere mixed with each other in the presence of 2 g. of an unsaturatedcopolymer consisting of ethylene, propylene, and dicyclopentadiene (52,44 and 4% by weight, respectively) per litre of hexane. The reactionmixture now contained much more copolymer, viz 33 g./l. Moreover, thereactor was much cleaner after this experiment than in the first case.

Example 6 In a continuous polymerization of a mixture of ethylene,propylene, and dicyclopentadiene two equal flows of heptane containing 5mmoles of C H AlCl and a mixture of 0.5 mmole of VOCl and 30 mmolesof'dicyclopentadiene, respectively; per litre were mixed immediatelybefore the polymerization reactor at a temperature of 23 C. and thenpassed into the reactor, where, at 2 atm. gauge and 30 C., the mixturewas brought into contact with a gas mixture consisting of 70% by volumeof propylene and 30% by volume of ethylene. The polymerization wascontinued for 60 hours, during which 1600 g. of polymer formed, 11 g. ofwhich stuck to the reactor wall.

When the unsaturated copolymer of ethylene, propylene, anddicyclopentadiene of Example 5 was added to the solution of C H AlCl inheptane, 1900 g. of polymer formed, only 1 gram of which stuck to thereactor wall.

Example 7 A continuous polymerization of a mixture of ethylene,propylene and dicyclopentadiene was carried out in the apparatus whichhas been drawn schematically in the figure.

The apparatus comprises a closed circuit, which comprises a pipe 1having an inner diameter of 50 mm. and a length of 6 m., a circulatingpump 8 and an inlineblender 2. The apparatus is further provided withfeed pipes 3, 4 and 5, which lead into the inline-blender 2, a feed pipe6, which leads into pipe 1, and an outlet pipe 7.

Through pipe 6 a mixture of gasoline, ethylene and propylene wascontinually charged into pipe 1, at a rate of l. of gasoline, 220 molesof ethylene and 830 moles of propylene per hour. Through pipes 3, 4 and5, respectively, 0.8 mole of aluminumsesquichloride, 0.08 mole ofvanadium-oxytrichloride and 6.75 moles of dicyclopentadiene, eachdissolved in 3 l. of gasoline, were fed per hour into the inline-blender2, wherein they were intimately mixed with each other, with the freshlyintroduced ethylene and propylene and with circulating previously formedpolymer. The circulating pump 8 was set to run at such a speed that itgave a throughput of 1000 l. per hour. The average residence time of thereactants in the circuit was about 2.5 minutes. The pressure in thecircuit was kept at 10 atm. gauge and the temperature at 25 C. Thepolymerization reaction started immediately after the reactants had beenmixed in the inline-blender and was practically completed within adistance of about 1 m. from the inline-blender, so that the actualpolymerization time was about 45 seconds. The polymer solution formedwas continuously withdrawn from the circuit through pipe 7. From thesolution a terpolymer was obtained in a yield of 8750 g. per hour andhaving ethylene, propylene and dicyclopentadiene contents of 56, 40 and4 percent by weight, respectively.

What is claimed is:

1. In a process for preparing unsaturated interpolymers, in which amixture of at least one alkene-l with the general formula RCH=CH whereinR is selected from the group consisting of a hydrogen atom, an alkyl,aryl, aralkyl, and alkaryl group, and/or a cyclo-alkene, and at leastone hydrocarbon with more than one double bond is polymerized in theliquid phase with the aid of a coordination catalyst containing anorganometallic compound of a metal selected from the metals consistingof the Groups I to III and Group IV-B of the Periodic System and acompound of a heavy metal selected from the metals consisting of theGroups IVA to VIIA and Group VIII of the Periodic System of the Elementsaccording to Mendeleef, the improvement which comprises mixing the saidcatalyst components in a liquid medium in the presence of 20 mg. or moreof a soluble unsaturated hydrocarbon polymer per mmole of saidorganometallic compound so that no catalyst precipitate is formed, andsubsequently passing the mixture into the polymerization zone.

2. A process according to claim 1, wherein the soluble unsaturatedpolymer comprises the interpolymer that is formed in the polymerization.

3. A process according to claim 1, wherein said soluble unsaturatedpolymer is used in an amount of 20-200 mg. per mmole of theorganometallic catalyst component.

4. A process according to claim 1, wherein the catalyst contains anorganic aluminum compound and a vanadium compound.

5. A process according to claim 2, wherein the catalyst contains anorganic aluminum compound and a vanadium compound.

6. A process according to claim 3, wherein the catalyst contains anorganic aluminum compound and a vanadium compound.

7. A process according to claim 1, wherein the soluble unsaturatedpolymer comprises a interpolymer of ethylene, propylene, and ahydrocarbon with two or more non-conjugated double bonds.

8. A process according to claim 3, wherein the soluble unsaturatedpolymer comprises a interpolymer of ethylene, propylene, and ahydrocarbon with two or more non-conjugated double bonds.

9. A process according to claim 4, wherein the soluble unsaturatedpolymer comprises a interpolymer of ethylene, propylene, and ahydrocarbon with two or more non-conjugated double bonds.

10. A process according to claim 1, wherein at least part of themonomers, in the ratio in which they are passed into the reaction zone,are also mixed with the catalyst components.

11. A process according to claim 4, wherein at least part of themonomers, in the ratio in which they are passed into the reaction zone,are also mixed with the catalyst components.

12. A process according to claim 9, wherein at least part of themonomers, in the ratio in which they are passed into the reaction zone,are also mixed with the catalyst components.

13. A process for preparing unsaturated interpolymers comprising mixingat least one alkene-l with the general formula RCH=CH wherein R isselected from the group consisting of a hydrogen atom, an alkyl, aryl,aralkyl and alkaryl group and/or a cyclo-alkene, at least onehydrocarbon with more than one double bond, a solvent, and coordinationcatalyst components in the presence of an unsaturated hydrocarbonpolymer at a temperature below C., and then passing the mixture into apolymerization zone maintained at a copolymerization temperature, saidcatalyst components comprising an organo-metallic compound of a metalselected from the metals consisting of the Groups I to III and GroupIV-B of the Periodic System and a compound of a heavy metal selectedfrom the metals consisting of the Groups IV-A to VII-A and Group VIII ofthe Periodic System, the amount of said unsaturated polymer added beingin an amount of 20-200 mg. per mmole of said organometallic compound.

14. A continuous process in accordance with claim 13 wherein additionalof said alkene-l and hydrocarbon with more than one double bondingredients are added to a portion of the solution leaving thepolymerization zone and recirculating this portion to the polymerizationzone.

15. A process according to claim 13 wherein the unsaturated polymeradded comprises the interpolymer that is formed in the polymerization.

16. A process for preparing unsaturated interpolymers comprising mixingcoordination catalyst components, a solvent, and at least onehydrocarbon with more than one double bond in the presence of anunsaturated hydrocarbon polymer, and then passing the mixture into apolymerization zone into contact with at least one alkene- 1 with thegeneral formula R-CH=CH wherein R is selected from the group consistingof a hydrogen atom, an alkyl, aryl, aralkyl and alkaryl group and/or acycloalkene, at a copolymerization temperature, said catalyst componentscomprising an organometallic compound of a metal selected from themetals consisting of the Groups I to III and Group IV-B of the PeriodicSystem and a 8 compound of a heavy metal selected from the metalsconsisting of the Groups IV-A to VII-A and Group VIII of the PeriodicSystem, according to Mendeleef, the amount of said unsaturated polymeradded being in an amount of 20-200 mg. per mmole of said organometalliccompound.

17. A process according to claim 16 wherein the unsaturated polymeradded comprises the interpolymer that is formed in the polymerization.

18. A continuous process in accordance with claim 16 wherein additionalof the hydrocarbon with more than one double bond is added to a portionof the solution leaving the polymerization zone and recirculating thisportion to the polymerization zone.

19. A process for preparing an unsaturated interpolymer of ethylene,propylene and dicyclopentadiene comprising mixing ethylene, propylene,dicyclopentadiene, and coordination catalyst components dissolved in asolvent in the presence of an unsaturated interpolymer of ethylene,propylene and dicyclopentadiene at a temperature below 0 C., and thenpassing the mixture into a polymerization zone maintained at acopolymerization temperature, said catalyst components comprising anorganometallic compound of a metal selected from the metals consistingof the Groups I to I11 and Group IV-B of the Periodic System and acompound of a heavy metal selected from the metals consisting of theGroups IV-A to VII-A and Group VIII of the Periodic System, according toMendeleef, the amount of said unsaturated interpolymer added being in anamount of 20-200 mg. per mmole of said organometallic compound.

20. A continuous process in accordance with claim 19 wherein additionalethylene, propylene and dicyclopentadiene are added to a portion of thesolution leaving the polymerization zone and recirculating this portionto the polymerization zone.

21. A process for preparing an unsaturated interpolymer of ethylene,propylene and dicyclopentadiene comprising mixing coordination catalystcomponents, a solvent, and dicyclopentadiene in the presence of anunsaturated interpolymer of ethylene, propylene and dicyclopentadiene,and then passing the mixture into a polymerization zone into contactwith a gas mixture of ethylene and propylene at a copolymerizationtemperature, said catalyst components comprising an organometalliccompound of a metal selected from the metals consisting of the Groups Ito III and Group IV-B of the Periodic System and a compound of a heavymetal selected from the metals consisting of the Groups IV-A to VII-Aand Group VIII of the Periodic System, the amount of said unsaturatedinterpolymer added being in an amount of 20-200 mg. per mmole of saidorganometallic compound.

22. A continuous process in accordance with claim 21 wherein additionaldicyclopentadiene is added to a portion of the solution leaving thepolymerization zone and recirculating this portion to the polymerizationzone.

References Cited UNITED STATES PATENTS 3,341,503 9/1967 Paige 260-80.78

JOSEPH L. SCHOFER, Primary Examiner ROGER S. BENJAMIN, AssistantExaminer US. Cl. X.R. 60-882

